Proven Tips for Animating Believable Lip Sync
Don't animate every syllable
When animating lip sync your first instinct might be to try to pose out the mouth shape for every syllable that you hear in the audio. This is a common mistake and will cause your character's jaw to open and close way more than it needs to. Instead, focus on the most important mouth shapes in the audio and blend over the rest. In reality this is how humans talk. Shoot some reference footage of yourself speaking the line and you'll be surprised how little the jaw actually moves.
Offset the lip sync for readability
Offsetting lip sync is something that is often forgotten or overlooked, but it is important to take into account. With animation, its all about readability and lip sync is no exception. For your audience to be able to read the lip sync you'll want to offset the jaw opening one to two frames before the audio is actually heard. If you have the jaw opening and closing each frame that the audio is heard your lip sync will feel like it's just slightly ahead of the audio.
Hit those closed mouth shapes
When it comes to mouth shapes some of the most important ones to hit properly are when the mouth is closed, like B, M, and P. You can't blend over these because you need them to read clearly. To do that you'll want to hold them for a couple frames, and pop open to the next mouth shape. For example, say your character is saying the word "but". If you blend over the "B" shape it will look like the mouth is saying "ut." To get the word to read properly, you'll want to hold the "B" shape for 2 frames and then pop open to "ut." Try it out and you'll see the difference!
Be the referenceIf you are having trouble coming up with the right mouth shapes, try whipping out a mirror. Many times there is no better way to find the right shapes than to look at yourself for reference. Say the dialogue out loud. Study how your mouth is blending between shapes and what kind of pose it's in for each word. If you wanted to take it a step further, try shooting video of yourself saying the dialogue and copy it to your computer to look at it frame-by-frame. This way you can really see the different types of shapes and movements your mouth is doing for each word.
Don't be afraid to exaggerate
When you think about it, lip sync typically happens very quickly. That's why it is extremely important that you have enough exaggeration in there so your animation can be read properly by the audience. Listen closely to your audio and mark all the moments where the character is speaking louder, even if its just a slight adjustment. Once you have those identified, use those marks as moments to push the mouth shapes further. Exaggerate the mouth for shapes like "W" and "O" so it'll be much easier to read. Have fun with it and remember you can always dial it back if you've gone too far. Next time you tackle a dialogue shot, try implementing these few techniques to help you create the killer lip sync that will truly enhance your shot and put it on the next level. If you want to see some of these techniques in action, check out the Facial Animation in Maya course. And check out these tips for creating impressive lip-syncing in CINEMA 4D.